How do Organisms Reproduce?

Sexual Reproduction

Reproduction in Human Beings

• Male Reproductive System

  1. Testes: A pair of testes are located inside scrotum which is present outside the abdominal cavity. Scrotum has a relatively lower temperature needed for the production of sperms.
     1. Male germ cell i.e., sperms are formed here.
     2. Testes release male sex hormone (testosterone).
     3. Its function is :
        • Regulate production of sperms.
        • Bring changes at puberty.
  2. Vas deferens: It passes sperms from testes up to urethra.
  3. Urethra: It is a common passage for both sperms and urine. Its outer covering is called a penis.
  4. Associated glands: Seminal vesicles and prostate gland add their secretion to the sperms. This fluid provides nourishment to sperms and make their transport easy. Sperm along with secretion of glands forms semen.

  

• Female Reproductive System

  The female reproductive system in human beings is composed of following parts:

  Ovary : A pair of the ovary is located in both sides of the abdomen.

  1. Female germ cells i.e., eggs are produced here.
  2. At the time of birth of a girl, thousands of immature eggs are present in the ovary.
  3. At the onset of puberty, some of these eggs start maturing.
  4. One egg is produced every month by one of the ovaries.

  Oviduct or Fallopian tube

  1. Receives the egg produced by the ovary and transfer it to the uterus.
  2. Fertilisation i.e., a fusion of gametes takes place here.

  Uterus: It is a bag-like structure where the development of the baby takes place.

  1. Uterus opens into the vagina through the cervix.

  

• What happens when the Egg is not Fertilised?

  When the egg is fertilised :

  1. The fertilized egg called zygote is planted in the uterus and develops into an embryo.
  2. The embryo gets nutrition from the mother’s blood with the help of a special tissue called placenta. It provides a large surface area for the exchange of glucose, oxygen and waste material.
  3. The time period from fertilization up to the birth of the baby is called gestation period. It is about 9 months.

  When the egg is not fertilised :

  1. The uterus prepares itself every month to receive a fertilized egg.
  2. The lining of the uterus becomes thick and spongy, required to support the embryo.
  3. When fertilisation had not taken place, this lining is not needed any longer.
  4. This lining breaks and comes out through vagina as blood and mucus.This cycle takes around 28 days every month and called menstruation.

• Reproductive Health

  Reproductive health means a total well-being in all aspects of reproduction i.e., physical, emotional, social and behavioural.

  Sexually Transmitted Diseases (STDs)

  1. Many diseases can be sexually transmitted such as :
     1. Bacterial: Gonorrhoea and syphilis 
     2. Viral: Warts and HIV-AIDS
  2. Use of condom prevents these infections to some extent.

  Contraception

  It is the avoidance of pregnancy, can be achieved by preventing the fertilisation of ova.

  Methods of contraception

  1. Physical barrier
     1. To prevent the union of egg and sperm.
     2. Use of condoms, cervical caps and diaphragm.
  2. Chemical methods
     1. Use of oral pills
     2. These change hormonal balance of body so that eggs are not released.
     3. May have side effects.
  3. Intrauterine contraceptive device (IUCD)
     1. Copper-T or loop is placed in the uterus to prevent pregnancy.
  4. Surgical methods
     1. In males, the vas deferens is blocked to prevent sperm transfer called vasectomy.
     2. In females, the fallopian tube is blocked to prevent egg transfer called tubectomy.

  Female Foeticide

  1. The practice of killing a female child inside the womb is called female foeticide.
  2. For a healthy society, a balanced sex ratio is needed that can be achieved by educating people to avoid malpractices like female foeticide and prenatal sex determination.
  3. Prenatal sex determination is a legal offence in our country so as to maintain a balanced sex ratio.

Sexual Reproduction in Flowering Plants

Why the Sexual Mode of Reproduction?